/* ================================================
   大学生AI技术分享网站样式表
   作者：AI技术分享团队
   版本：1.0
   描述：网站整体样式定义，包含响应式设计和动画效果
================================================ */

/* ==================== 基础样式重置 ==================== */
/* 重置所有元素的默认边距和内边距，使用border-box盒模型 */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

/* 页面主体样式 */
body {
  font-family: "Segoe UI", "Microsoft YaHei", "微软雅黑", Arial, sans-serif;
  line-height: 1.6;
  color: #333;
  background-color: #f8f9fa;
}

/* 平滑滚动效果 */
html {
  scroll-behavior: smooth;
}

/* ==================== 头部导航样式 ==================== */
/* 页面头部区域样式 */
header {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%); /* 紫色渐变背景 */
  color: white;
  padding: 0;
  position: sticky; /* 粘性定位，页面滚动时固定在顶部 */
  top: 0;
  z-index: 1000; /* 确保导航栏在最上层 */
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1); /* 底部阴影效果 */
}

/* 导航栏容器样式 */
nav {
  max-width: 1200px; /* 最大宽度限制 */
  margin: 0 auto; /* 水平居中 */
  display: flex;
  justify-content: space-between; /* 两端对齐 */
  align-items: center;
  padding: 1rem 2rem;
  position: relative;
  min-height: 60px;
}

/* Logo区域样式 */
.logo h1 {
  font-size: 1.8rem;
  font-weight: bold;
  display: flex;
  align-items: center;
  gap: 0.5rem; /* 图标和文字间距 */
  margin: 0;
  z-index: 1002;
}

/* 导航链接列表样式 */
.nav-links {
  display: flex;
  list-style: none;
  gap: 1.5rem; /* 链接间距 */
  margin: 0;
  padding: 0;
  align-items: center;
}

/* 导航链接样式 */
.nav-links a {
  color: white;
  text-decoration: none;
  font-weight: 500;
  padding: 0.75rem 1.25rem;
  border-radius: 25px; /* 圆角效果 */
  transition: all 0.3s ease; /* 平滑过渡效果 */
  position: relative;
  white-space: nowrap;
}

/* 导航链接悬停和激活状态 */
.nav-links a:hover,
.nav-links a.active {
  background-color: rgba(255, 255, 255, 0.2); /* 半透明白色背景 */
  transform: translateY(-2px); /* 轻微上移效果 */
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
}

/* ==================== 主要内容区域 ==================== */
/* 页面主体内容区域样式 */
main {
  max-width: 1200px; /* 最大宽度限制 */
  margin: 0 auto; /* 水平居中 */
  padding: 2rem;
  min-height: calc(100vh - 200px); /* 最小高度，确保页脚在底部 */
}

/* ==================== 页面头部样式 ==================== */
/* 内容页面的头部区域样式 */
.page-header {
  text-align: center;
  margin-bottom: 3rem;
  padding: 3rem 0;
  background: linear-gradient(135deg, #f093fb 0%, #f5576c 100%); /* 粉色渐变背景 */
  color: white;
  border-radius: 15px; /* 圆角效果 */
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1); /* 阴影效果 */
}

/* 页面头部标题样式 */
.page-header h2 {
  font-size: 2.5rem;
  margin-bottom: 1rem;
  font-weight: bold;
}

/* 页面头部描述文字样式 */
.page-header p {
  font-size: 1.2rem;
  opacity: 0.9; /* 轻微透明效果 */
}

/* 内容区块样式 */
.content-section {
  margin-bottom: 3rem;
}

.concept-card {
  background: white;
  padding: 2rem;
  margin-bottom: 2rem;
  border-radius: 15px;
  box-shadow: 0 5px 20px rgba(0, 0, 0, 0.08);
  transition:
    transform 0.3s ease,
    box-shadow 0.3s ease;
}

.concept-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 15px 40px rgba(0, 0, 0, 0.12);
}

.concept-card h3 {
  color: #667eea;
  font-size: 1.5rem;
  margin-bottom: 1rem;
  border-left: 4px solid #667eea;
  padding-left: 1rem;
}

.concept-content {
  line-height: 1.8;
  color: #555;
}

.highlight-box {
  background: linear-gradient(135deg, #ffecd2 0%, #fcb69f 100%);
  padding: 1.5rem;
  border-radius: 10px;
  margin: 1.5rem 0;
  border-left: 4px solid #ff6b6b;
}

/* 主页英雄区域 */
.hero {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3rem;
  align-items: center;
  min-height: 60vh;
  margin-bottom: 4rem;
}

.hero-content h2 {
  font-size: 3rem;
  color: #333;
  margin-bottom: 1rem;
  line-height: 1.2;
}

.hero-content p {
  font-size: 1.3rem;
  color: #666;
  margin-bottom: 2rem;
}

.cta-button {
  display: inline-block;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: white;
  padding: 1rem 2rem;
  text-decoration: none;
  border-radius: 50px;
  font-weight: bold;
  font-size: 1.1rem;
  transition: all 0.3s ease;
  box-shadow: 0 5px 15px rgba(102, 126, 234, 0.4);
}

.cta-button:hover {
  transform: translateY(-3px);
  box-shadow: 0 10px 25px rgba(102, 126, 234, 0.6);
}

.hero-image {
  display: flex;
  justify-content: center;
  align-items: center;
}

.ai-icon {
  font-size: 8rem;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  animation: float 3s ease-in-out infinite;
}

@keyframes float {
  0%,
  100% {
    transform: translateY(0px);
  }
  50% {
    transform: translateY(-20px);
  }
}

/* 特性网格 */
.features {
  text-align: center;
  margin-bottom: 4rem;
}

.features h3 {
  font-size: 2.2rem;
  color: #333;
  margin-bottom: 3rem;
}

.feature-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 2rem;
  margin-top: 2rem;
}

.feature-card {
  background: white;
  padding: 2rem;
  border-radius: 15px;
  box-shadow: 0 5px 20px rgba(0, 0, 0, 0.08);
  transition: transform 0.3s ease;
  text-align: center;
}

.feature-card:hover {
  transform: translateY(-10px);
}

.feature-icon {
  font-size: 3rem;
  margin-bottom: 1rem;
}

.feature-card h4 {
  color: #667eea;
  font-size: 1.3rem;
  margin-bottom: 1rem;
}

/* 学习路径 */
.learning-path {
  text-align: center;
  margin-bottom: 4rem;
}

.learning-path h3 {
  font-size: 2.2rem;
  color: #333;
  margin-bottom: 3rem;
}

.path-container {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 2rem;
  flex-wrap: wrap;
}

.path-step {
  background: white;
  padding: 1.5rem 2rem;
  border-radius: 15px;
  box-shadow: 0 5px 20px rgba(0, 0, 0, 0.08);
  text-align: center;
  min-width: 150px;
}

.step-number {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: white;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: bold;
  font-size: 1.2rem;
  margin: 0 auto 1rem;
}

.path-arrow {
  font-size: 2rem;
  color: #667eea;
  font-weight: bold;
}

/* 时间线样式 */
.timeline {
  position: relative;
  padding-left: 2rem;
}

.timeline::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 3px;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  border-radius: 2px;
}

.timeline-item {
  position: relative;
  margin-bottom: 2rem;
  padding-left: 2rem;
}

.timeline-item::before {
  content: "";
  position: absolute;
  left: -1.5rem;
  top: 0.5rem;
  width: 12px;
  height: 12px;
  background: #667eea;
  border-radius: 50%;
  border: 3px solid white;
  box-shadow: 0 0 0 3px #667eea;
}

.timeline-year {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: white;
  padding: 0.5rem 1rem;
  border-radius: 20px;
  font-weight: bold;
  display: inline-block;
  margin-bottom: 0.5rem;
}

/* 网格布局 */
.branch-grid,
.ml-types-grid,
.algorithms-grid,
.architecture-grid,
.applications-grid,
.platforms-grid,
.books-grid,
.tools-grid,
.tips-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 2rem;
  margin-top: 2rem;
}

.branch-item,
.ml-type-card,
.algorithm-category,
.architecture-card,
.application-category,
.platform-card,
.book-category,
.tool-category,
.tip-card {
  background: white;
  padding: 1.5rem;
  border-radius: 15px;
  box-shadow: 0 5px 20px rgba(0, 0, 0, 0.08);
  transition: transform 0.3s ease;
}

.branch-item:hover,
.ml-type-card:hover,
.algorithm-category:hover,
.architecture-card:hover,
.platform-card:hover,
.tip-card:hover {
  transform: translateY(-5px);
}

.branch-icon,
.type-icon,
.arch-icon,
.platform-logo,
.tip-icon {
  font-size: 2.5rem;
  margin-bottom: 1rem;
  text-align: center;
}

/* 算法列表 */
.algorithm-item {
  background: #f8f9fa;
  padding: 1rem;
  margin: 0.5rem 0;
  border-radius: 8px;
  border-left: 4px solid #667eea;
}

.algorithm-item strong {
  color: #667eea;
}

/* 工作流程 */
.workflow-steps {
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 1rem;
  margin-top: 2rem;
}

.workflow-step {
  background: white;
  padding: 1.5rem;
  border-radius: 15px;
  box-shadow: 0 5px 20px rgba(0, 0, 0, 0.08);
  text-align: center;
  flex: 1;
  min-width: 150px;
}

/* 学习路径卡片 */
.learning-paths {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
  gap: 2rem;
  margin-top: 2rem;
}

.path-card {
  background: white;
  border-radius: 15px;
  box-shadow: 0 5px 20px rgba(0, 0, 0, 0.08);
  overflow: hidden;
  transition: transform 0.3s ease;
}

.path-card:hover {
  transform: translateY(-5px);
}

.path-header {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: white;
  padding: 1.5rem;
  text-align: center;
}

.path-icon {
  font-size: 2.5rem;
  margin-bottom: 0.5rem;
}

.path-content {
  padding: 1.5rem;
}

.path-stage {
  background: #f8f9fa;
  padding: 1rem;
  margin: 1rem 0;
  border-radius: 10px;
  border-left: 4px solid #667eea;
}

/* 导航链接 */
.navigation-links {
  display: flex;
  justify-content: space-between;
  margin-top: 3rem;
  padding-top: 2rem;
  border-top: 2px solid #e9ecef;
}

.prev-page,
.next-page {
  display: inline-block;
  padding: 1rem 2rem;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: white;
  text-decoration: none;
  border-radius: 25px;
  font-weight: bold;
  transition: all 0.3s ease;
  box-shadow: 0 5px 15px rgba(102, 126, 234, 0.4);
}

.prev-page:hover,
.next-page:hover {
  transform: translateX(-5px);
  box-shadow: 0 10px 25px rgba(102, 126, 234, 0.6);
}

.next-page:hover {
  transform: translateX(5px);
}

/* 页脚样式 */
footer {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: white;
  text-align: center;
  padding: 2rem 0;
  margin-top: 4rem;
}

.footer-content p {
  font-size: 1.1rem;
  opacity: 0.9;
}

/* 响应式设计 */
@media (max-width: 768px) {
  nav {
    flex-direction: column;
    gap: 1rem;
    padding: 1rem;
  }

  .nav-links {
    flex-wrap: wrap;
    justify-content: center;
    gap: 1rem;
  }

  .hero {
    grid-template-columns: 1fr;
    text-align: center;
    gap: 2rem;
  }

  .hero-content h2 {
    font-size: 2rem;
  }

  .path-container {
    flex-direction: column;
    gap: 1rem;
  }

  .path-arrow {
    transform: rotate(90deg);
  }

  .workflow-steps {
    flex-direction: column;
  }

  .navigation-links {
    flex-direction: column;
    gap: 1rem;
    align-items: center;
  }

  main {
    padding: 1rem;
  }

  .page-header h2 {
    font-size: 2rem;
  }
}

@media (max-width: 480px) {
  .hero-content h2 {
    font-size: 1.8rem;
  }

  .hero-content p {
    font-size: 1.1rem;
  }

  .feature-grid,
  .branch-grid,
  .ml-types-grid,
  .algorithms-grid,
  .architecture-grid,
  .applications-grid,
  .platforms-grid,
  .books-grid,
  .tools-grid,
  .tips-grid,
  .learning-paths {
    grid-template-columns: 1fr;
  }

  .concept-card {
    padding: 1.5rem;
  }

  .tip-card {
    padding: 1.5rem;
  }

  .tip-icon {
    font-size: 2.5rem;
    margin-bottom: 1rem;
  }

  .tip-card h4 {
    font-size: 1.2rem;
  }
}

/* 动画效果 */
@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(30px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.concept-card,
.feature-card,
.path-card,
.timeline-item,
.tip-card {
  animation: fadeInUp 0.6s ease-out;
}

/* 特殊样式 */
.neuron-formula {
  background: #2c3e50;
  color: #ecf0f1;
  padding: 1rem;
  border-radius: 8px;
  font-family: "Courier New", monospace;
  text-align: center;
  margin: 1rem 0;
  font-size: 1.1rem;
}

.arch-features,
.framework-features,
.tool-features,
.stage-resources {
  background: #e8f4f8;
  padding: 1rem;
  border-radius: 8px;
  margin-top: 1rem;
  font-size: 0.9rem;
}

.case-impact {
  background: linear-gradient(135deg, #d4fc79 0%, #96e6a1 100%);
  padding: 1rem;
  border-radius: 8px;
  margin-top: 1rem;
  font-weight: bold;
}

.book-level {
  color: #f39c12;
  font-weight: bold;
  margin-top: 0.5rem;
}

/* 学习建议卡片增强样式 */
.tip-card {
  background: white;
  padding: 2rem;
  border-radius: 15px;
  box-shadow: 0 5px 20px rgba(0, 0, 0, 0.08);
  transition:
    transform 0.3s ease,
    box-shadow 0.3s ease;
  text-align: center;
  border: 1px solid #f0f0f0;
}

.tip-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 15px 40px rgba(0, 0, 0, 0.12);
}

.tip-icon {
  font-size: 3rem;
  margin-bottom: 1.5rem;
  text-align: center;
  display: block;
}

.tip-card h4 {
  color: #667eea;
  font-size: 1.3rem;
  margin-bottom: 1rem;
  font-weight: bold;
}

.tip-card p {
  color: #555;
  line-height: 1.7;
  font-size: 1rem;
}

/* 学习建议部分标题样式 */
.concept-card h3 {
  color: #667eea;
  font-size: 1.8rem;
  margin-bottom: 1.5rem;
  border-left: 4px solid #667eea;
  padding-left: 1rem;
  font-weight: bold;
}

/* ==================== JavaScript交互样式 ==================== */

/* ==================== 滚动导航栏样式 ==================== */
/* 滚动时的导航栏样式 */
header.scrolled {
  background: rgba(102, 126, 234, 0.95);
  backdrop-filter: blur(10px);
  box-shadow: 0 2px 20px rgba(0, 0, 0, 0.1);
  padding: 0.5rem 0;
}

/* ==================== 返回顶部按钮样式 ==================== */
.scroll-to-top {
  position: fixed;
  bottom: 30px;
  right: 30px;
  width: 50px;
  height: 50px;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: white;
  border: none;
  border-radius: 50%;
  font-size: 20px;
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transition: all 0.3s ease;
  z-index: 1000;
  box-shadow: 0 4px 15px rgba(0, 0, 0, 0.2);
}

.scroll-to-top.visible {
  opacity: 1;
  visibility: visible;
}

.scroll-to-top:hover {
  transform: translateY(-3px);
  box-shadow: 0 6px 20px rgba(0, 0, 0, 0.3);
}

/* ==================== 卡片悬停动画样式 ==================== */
/* 为所有卡片添加悬停动画基础样式 */
.feature-card,
.concept-card,
.resource-card {
  transition: all 0.3s ease;
  cursor: pointer;
}

/* 卡片悬停效果增强 */
.feature-card:hover,
.concept-card:hover,
.resource-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.15);
}

/* ==================== 导航链接激活状态样式 ==================== */
/* 当前活动页面的导航链接样式 */
.nav-links a.active {
  background-color: rgba(255, 255, 255, 0.3);
  font-weight: 600;
}

/* 导航链接激活状态的伪元素指示器 */
.nav-links a.active::after {
  content: '';
  position: absolute;
  bottom: -5px;
  left: 50%;
  transform: translateX(-50%);
  width: 6px;
  height: 6px;
  background-color: white;
  border-radius: 50%;
}

/* ==================== 响应式设计 - JavaScript交互样式 ==================== */
@media (max-width: 768px) {
  .scroll-to-top {
    bottom: 20px;
    right: 20px;
    width: 45px;
    height: 45px;
    font-size: 18px;
  }
}

@media (max-width: 480px) {
  .scroll-to-top {
    bottom: 15px;
    right: 15px;
    width: 40px;
    height: 40px;
    font-size: 16px;
  }
}

/* ==================== 性能优化样式 ==================== */
/* 滚动进度条样式 */
.scroll-progress-container {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 3px;
  background: rgba(0, 0, 0, 0.1);
  z-index: 1001;
}

.scroll-progress {
  height: 100%;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  width: 0%;
  transition: width 0.1s ease;
}

/* 图片懒加载样式 */
img.lazy {
  opacity: 0;
  transition: opacity 0.3s ease;
}

img.lazy.loaded {
  opacity: 1;
}

/* 加载动画样式 */
.loading-spinner {
  display: inline-block;
  width: 20px;
  height: 20px;
  border: 3px solid #f3f3f3;
  border-top: 3px solid #667eea;
  border-radius: 50%;
  animation: spin 1s linear infinite;
}

@keyframes spin {
  0% { transform: rotate(0deg); }
  100% { transform: rotate(360deg); }
}

/* 性能优化提示样式 */
.performance-hint {
  position: fixed;
  bottom: 20px;
  left: 20px;
  background: #667eea;
  color: white;
  padding: 10px 15px;
  border-radius: 5px;
  font-size: 0.8rem;
  z-index: 1000;
  opacity: 0.9;
  display: none;
}

/* 资源加载状态指示器 */
.resource-loader {
  position: fixed;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  background: rgba(0, 0, 0, 0.8);
  color: white;
  padding: 20px;
  border-radius: 10px;
  z-index: 9999;
  display: none;
}

/* ==================== 响应式设计优化 ==================== */
/* 移动设备优化：针对小屏幕设备的样式调整 */

/* 平板设备：屏幕宽度小于1024px */
@media (max-width: 1024px) {
  /* 调整主内容区域最大宽度 */
  main {
    max-width: 90%;
    padding: 0 20px;
  }
  
  /* 导航栏调整为垂直布局 */
  nav {
    flex-direction: column;
    align-items: flex-start;
  }
  
  /* 导航链接垂直排列 */
  .nav-links {
    flex-direction: column;
    width: 100%;
    margin-top: 10px;
  }
  
  /* 特性网格调整为2列 */
  .feature-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: 20px;
  }
  
  /* 学习路径调整为垂直排列 */
  .path-container {
    flex-direction: column;
    align-items: center;
  }
  
  .path-arrow {
    transform: rotate(90deg);
    margin: 10px 0;
  }
}

/* 手机设备：屏幕宽度小于768px */
@media (max-width: 768px) {
  /* 进一步缩小主内容区域 */
  main {
    max-width: 95%;
    padding: 0 15px;
  }
  
  /* 英雄区域调整为垂直布局 */
  .hero {
    flex-direction: column;
    text-align: center;
  }
  
  .hero-content {
    margin-bottom: 30px;
  }
  
  /* 特性网格调整为单列 */
  .feature-grid {
    grid-template-columns: 1fr;
    gap: 15px;
  }
  
  /* 概念卡片调整为垂直布局 */
  .concept-cards {
    grid-template-columns: 1fr;
  }
  
  /* 资源列表调整为单列 */
  .resource-list {
    grid-template-columns: 1fr;
  }
  
  /* 调整字体大小以适应小屏幕 */
  h1 {
    font-size: 1.8rem;
  }
  
  h2 {
    font-size: 1.5rem;
  }
  
  h3 {
    font-size: 1.3rem;
  }
  
  /* 调整按钮大小 */
  .cta-button {
    padding: 10px 20px;
    font-size: 1rem;
  }
}

/* 超小屏幕设备：屏幕宽度小于480px */
@media (max-width: 480px) {
  /* 进一步调整布局和字体大小 */
  main {
    max-width: 100%;
    padding: 0 10px;
  }
  
  /* 调整标题字体大小 */
  h1 {
    font-size: 1.5rem;
  }
  
  h2 {
    font-size: 1.3rem;
  }
  
  h3 {
    font-size: 1.1rem;
  }
  
  /* 调整段落字体大小 */
  p {
    font-size: 0.9rem;
    line-height: 1.4;
  }
  
  /* 调整卡片内边距 */
  .feature-card, .concept-card, .resource-card {
    padding: 15px;
  }
  
  /* 调整导航栏Logo大小 */
  .logo h1 {
    font-size: 1.3rem;
  }
}

/* ==================== 移动端汉堡菜单 ==================== */
/* 汉堡菜单按钮样式 */
.menu-toggle {
  display: none;
  background: none;
  border: none;
  font-size: 1.5rem;
  cursor: pointer;
  color: #333;
  padding: 10px;
}

/* 移动端导航栏样式 */
@media (max-width: 768px) {
  /* 导航栏容器适配 */
  nav {
    position: relative;
    padding: 0.5rem 1rem;
    flex-wrap: wrap;
    min-height: 50px;
  }
  
  /* Logo区域适配 */
  .logo h1 {
    font-size: 1.5rem;
    z-index: 1002;
  }
  
  /* 显示汉堡菜单按钮 */
  .menu-toggle {
    display: flex !important;
    position: absolute;
    right: 15px;
    top: 50%;
    transform: translateY(-50%);
    z-index: 1001;
    background: rgba(255, 255, 255, 0.2);
    border: none;
    border-radius: 5px;
    width: 40px;
    height: 40px;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    color: white;
    cursor: pointer;
    transition: background 0.3s ease;
  }
  
  .menu-toggle:hover {
    background: rgba(255, 255, 255, 0.3);
  }
  
  /* 默认隐藏导航链接 */
  .nav-links {
    display: none;
    width: 100%;
    background: white;
    position: absolute;
    top: 100%;
    left: 0;
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
    border-radius: 0 0 10px 10px;
    z-index: 1000;
    max-height: 70vh;
    overflow-y: auto;
    margin: 0;
    padding: 0;
  }
  
  /* 导航链接显示时的样式 */
  .nav-links.active {
    display: flex;
    flex-direction: column;
  }
  
  /* 导航链接项样式 */
  .nav-links li {
    width: 100%;
    text-align: center;
    margin: 0;
    border-bottom: 1px solid #f0f0f0;
  }
  
  .nav-links li:last-child {
    border-bottom: none;
  }
  
  .nav-links a {
    display: block;
    padding: 15px 20px;
    color: #333;
    text-decoration: none;
    font-weight: 500;
    transition: all 0.3s ease;
    border-radius: 0;
    text-align: center;
  }
  
  .nav-links a:hover,
  .nav-links a.active {
    background-color: #667eea;
    color: white;
    transform: none;
  }
  
  /* 导航栏滚动状态适配 */
  header.scrolled .nav-links {
    top: 100%;
  }
  
  /* 隐藏桌面端导航链接 */
  .nav-links:not(.active) {
    display: none;
  }
}

/* ==================== 内容扩展与交互组件样式 ==================== */

/* 信息框样式 */
.info-box {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  border-radius: 12px;
  padding: 20px;
  margin: 20px 0;
  color: white;
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.1);
}

.info-box h4 {
  margin-bottom: 15px;
  font-size: 1.3em;
  text-align: center;
}

.classification-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 20px;
  margin-top: 15px;
}

.classification-item {
  background: rgba(255, 255, 255, 0.1);
  padding: 15px;
  border-radius: 8px;
  backdrop-filter: blur(10px);
}

.classification-item h5 {
  margin-bottom: 10px;
  font-size: 1.1em;
  color: #f8f9fa;
}

.classification-item p {
  font-size: 0.9em;
  line-height: 1.4;
}

/* 交互式组件样式 */
.interactive-component {
  background: #f8f9fa;
  border: 2px solid #e9ecef;
  border-radius: 12px;
  padding: 20px;
  margin: 25px 0;
}

.interactive-component h4 {
  color: #495057;
  margin-bottom: 15px;
  text-align: center;
}

.quiz-container {
  max-width: 500px;
  margin: 0 auto;
}

.quiz-question p {
  font-weight: 600;
  margin-bottom: 15px;
  color: #343a40;
}

.quiz-options {
  display: grid;
  gap: 10px;
  margin-bottom: 15px;
}

.quiz-option {
  padding: 12px 20px;
  border: 2px solid #dee2e6;
  border-radius: 8px;
  background: white;
  cursor: pointer;
  transition: all 0.3s ease;
  font-size: 0.95em;
}

.quiz-option:hover {
  border-color: #007bff;
  background: #f8f9ff;
}

.quiz-option.correct {
  border-color: #28a745;
  background: #d4edda;
  color: #155724;
}

.quiz-option.incorrect {
  border-color: #dc3545;
  background: #f8d7da;
  color: #721c24;
}

.quiz-feedback {
  padding: 10px;
  border-radius: 6px;
  text-align: center;
  font-weight: 600;
  display: none;
}

.quiz-feedback.correct {
  background: #d4edda;
  color: #155724;
  display: block;
}

.quiz-feedback.incorrect {
  background: #f8d7da;
  color: #721c24;
  display: block;
}

/* 移动端交互组件响应式 */
@media (max-width: 768px) {
  .classification-grid {
    grid-template-columns: 1fr;
    gap: 15px;
  }
  
  .interactive-component {
    padding: 15px;
    margin: 20px 0;
  }
  
  .quiz-option {
    padding: 10px 15px;
    font-size: 0.9em;
  }
}

/* ==================== 多媒体内容样式 ==================== */

/* 多媒体展示区域样式 */
.multimedia-section {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
  gap: 30px;
  margin-top: 20px;
}

.media-item {
  background: white;
  border-radius: 12px;
  padding: 20px;
  box-shadow: 0 5px 20px rgba(0, 0, 0, 0.08);
  transition: transform 0.3s ease;
}

.media-item:hover {
  transform: translateY(-5px);
}

.media-item h4 {
  color: #667eea;
  margin-bottom: 15px;
  font-size: 1.2em;
  border-bottom: 2px solid #f0f0f0;
  padding-bottom: 10px;
}

/* 图片占位符样式 */
.image-placeholder {
  position: relative;
  background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
  border-radius: 8px;
  min-height: 200px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 15px;
  overflow: hidden;
}

.image-placeholder img {
  width: 100%;
  height: auto;
  border-radius: 6px;
  transition: transform 0.3s ease;
}

.image-placeholder img:hover {
  transform: scale(1.02);
}

.placeholder-text {
  color: #6c757d;
  font-style: italic;
  text-align: center;
  padding: 20px;
}

/* 视频容器样式 */
.video-container {
  position: relative;
  background: #000;
  border-radius: 8px;
  overflow: hidden;
  margin-bottom: 15px;
}

.video-container video {
  width: 100%;
  height: auto;
  display: block;
}

.video-caption {
  background: #f8f9fa;
  padding: 15px;
  border-radius: 0 0 8px 8px;
}

.video-caption p {
  margin: 5px 0;
  font-size: 0.9em;
  color: #6c757d;
}

.video-caption strong {
  color: #495057;
}

.media-description {
  color: #6c757d;
  font-size: 0.9em;
  line-height: 1.5;
  margin-top: 10px;
}

/* 多媒体内容响应式设计 */
@media (max-width: 768px) {
  .multimedia-section {
    grid-template-columns: 1fr;
    gap: 20px;
  }
  
  .media-item {
    padding: 15px;
  }
  
  .image-placeholder {
    min-height: 150px;
  }
  
  .video-caption {
    padding: 10px;
  }
}

/* 图片懒加载动画 */
img.lazy {
  opacity: 0;
  transition: opacity 0.3s ease;
}

img.lazy.loaded {
  opacity: 1;
}

/* 视频加载状态指示器 */
.video-loading {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  color: white;
  font-size: 1.2em;
}

/* 多媒体内容无障碍支持 */
.image-placeholder:focus,
.video-container:focus {
  outline: 2px solid #667eea;
  outline-offset: 2px;
}

/* 高对比度模式支持 */
@media (prefers-contrast: high) {
  .media-item {
    border: 2px solid #000;
  }
  
  .image-placeholder {
    background: #fff;
    border: 1px solid #000;
  }
}

/* ==================== 搜索功能样式 ==================== */

/* 搜索容器样式 */
.search-container {
  position: relative;
  max-width: 500px;
  margin: 0 auto;
  padding: 0 2rem;
}

.search-box {
  position: relative;
  display: flex;
  align-items: center;
  background: rgba(255, 255, 255, 0.1);
  border-radius: 25px;
  padding: 5px;
  backdrop-filter: blur(10px);
  border: 1px solid rgba(255, 255, 255, 0.2);
}

#search-input {
  flex: 1;
  border: none;
  background: transparent;
  color: white;
  padding: 10px 15px;
  font-size: 1rem;
  outline: none;
}

#search-input::placeholder {
  color: rgba(255, 255, 255, 0.7);
}

#search-button, #clear-search {
  background: transparent;
  border: none;
  color: white;
  padding: 8px 12px;
  cursor: pointer;
  border-radius: 50%;
  transition: background 0.3s ease;
}

#search-button:hover, #clear-search:hover {
  background: rgba(255, 255, 255, 0.2);
}

/* 搜索结果样式 */
.search-results {
  position: absolute;
  top: 100%;
  left: 2rem;
  right: 2rem;
  background: white;
  border-radius: 10px;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.2);
  z-index: 1000;
  max-height: 400px;
  overflow-y: auto;
  margin-top: 10px;
}

.results-header {
  padding: 15px 20px;
  border-bottom: 1px solid #e9ecef;
  background: #f8f9fa;
  border-radius: 10px 10px 0 0;
}

.results-header p {
  margin: 0;
  color: #6c757d;
}

.results-list {
  padding: 10px 0;
}

.search-result-item {
  padding: 15px 20px;
  border-bottom: 1px solid #f0f0f0;
  cursor: pointer;
  transition: background 0.2s ease;
}

.search-result-item:hover {
  background: #f8f9fa;
}

.search-result-item:last-child {
  border-bottom: none;
}

.search-result-item h4 {
  margin: 0 0 5px 0;
  color: #333;
  font-size: 1.1em;
}

.search-result-item h4 mark {
  background: #ffeb3b;
  padding: 2px 4px;
  border-radius: 3px;
}

.result-category {
  font-size: 0.8em;
  color: #667eea;
  font-weight: bold;
  margin: 0 0 8px 0;
}

.result-content {
  font-size: 0.9em;
  color: #666;
  line-height: 1.4;
  margin: 0 0 10px 0;
}

.result-content mark {
  background: #ffeb3b;
  padding: 1px 3px;
  border-radius: 2px;
}

.result-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 5px;
  margin-bottom: 10px;
}

.result-tag {
  background: #e9ecef;
  color: #495057;
  padding: 2px 8px;
  border-radius: 12px;
  font-size: 0.8em;
}

.result-link {
  color: #667eea;
  text-decoration: none;
  font-size: 0.9em;
  font-weight: 500;
}

.result-link:hover {
  text-decoration: underline;
}

/* 无结果样式 */
.no-results {
  padding: 20px;
  text-align: center;
}

.no-results p {
  margin: 0 0 15px 0;
  color: #6c757d;
}

.suggestion-categories {
  display: flex;
  gap: 10px;
  justify-content: center;
  flex-wrap: wrap;
}

.suggestion-category {
  background: #667eea;
  color: white;
  border: none;
  padding: 8px 15px;
  border-radius: 20px;
  font-size: 0.9em;
  cursor: pointer;
  transition: background 0.3s ease;
}

.suggestion-category:hover {
  background: #5a6fd8;
}

/* 搜索建议样式 */
.search-suggestions {
  position: absolute;
  top: 100%;
  left: 2rem;
  right: 2rem;
  background: white;
  border-radius: 10px;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.2);
  z-index: 1000;
  margin-top: 10px;
}

.suggestions-list {
  padding: 15px 20px;
}

.suggestions-list p {
  margin: 0 0 10px 0;
  color: #6c757d;
  font-size: 0.9em;
}

.suggestion-tag {
  background: #f8f9fa;
  border: 1px solid #e9ecef;
  color: #495057;
  padding: 5px 10px;
  border-radius: 15px;
  font-size: 0.8em;
  cursor: pointer;
  margin: 0 5px 5px 0;
  transition: all 0.3s ease;
}

.suggestion-tag:hover {
  background: #667eea;
  color: white;
  border-color: #667eea;
}

/* 搜索功能响应式设计 */
@media (max-width: 768px) {
  .search-container {
    padding: 0 1rem;
    max-width: 100%;
  }
  
  .search-results,
  .search-suggestions {
    left: 1rem;
    right: 1rem;
  }
  
  .suggestion-categories {
    flex-direction: column;
    align-items: center;
  }
  
  .suggestion-category {
    width: 100%;
    max-width: 200px;
  }
}

/* 滚动条样式 */
.search-results::-webkit-scrollbar {
  width: 6px;
}

.search-results::-webkit-scrollbar-track {
  background: #f1f1f1;
  border-radius: 3px;
}

.search-results::-webkit-scrollbar-thumb {
  background: #c1c1c1;
  border-radius: 3px;
}

.search-results::-webkit-scrollbar-thumb:hover {
  background: #a8a8a8;
}

/* ==================== 书签功能样式 ==================== */

/* 书签按钮样式 */
.bookmark-button {
  position: fixed;
  top: 100px;
  right: 20px;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: white;
  border: none;
  border-radius: 25px;
  padding: 12px 20px;
  cursor: pointer;
  box-shadow: 0 4px 15px rgba(102, 126, 234, 0.3);
  z-index: 999;
  display: flex;
  align-items: center;
  gap: 8px;
  transition: all 0.3s ease;
}

.bookmark-button:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(102, 126, 234, 0.4);
}

.bookmark-button.active {
  background: linear-gradient(135deg, #764ba2 0%, #667eea 100%);
}

.bookmark-button.has-bookmarks .bookmark-icon {
  color: #ffeb3b;
}

.bookmark-icon {
  font-size: 1.2em;
}

.bookmark-text {
  font-weight: 500;
}

/* 书签面板样式 */
.bookmark-panel {
  position: fixed;
  top: 150px;
  right: 20px;
  width: 350px;
  max-width: 90vw;
  background: white;
  border-radius: 10px;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.2);
  z-index: 1000;
  max-height: 500px;
  overflow: hidden;
  display: flex;
  flex-direction: column;
}

.bookmark-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 15px 20px;
  border-bottom: 1px solid #e9ecef;
  background: #f8f9fa;
}

.bookmark-header h3 {
  margin: 0;
  color: #333;
  font-size: 1.2em;
}

#close-bookmark-panel {
  background: none;
  border: none;
  font-size: 1.2em;
  cursor: pointer;
  color: #6c757d;
  padding: 5px;
  border-radius: 3px;
}

#close-bookmark-panel:hover {
  background: #e9ecef;
  color: #333;
}

.bookmark-list {
  flex: 1;
  overflow-y: auto;
  max-height: 350px;
  padding: 10px 0;
}

.empty-bookmarks {
  padding: 40px 20px;
  text-align: center;
  color: #6c757d;
}

.empty-bookmarks p {
  margin: 5px 0;
}

.bookmark-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 12px 20px;
  border-bottom: 1px solid #f0f0f0;
  transition: background 0.2s ease;
}

.bookmark-item:hover {
  background: #f8f9fa;
}

.bookmark-item:last-child {
  border-bottom: none;
}

.bookmark-content h4 {
  margin: 0 0 5px 0;
  color: #333;
  font-size: 1em;
  font-weight: 600;
}

.bookmark-page {
  margin: 0 0 3px 0;
  color: #6c757d;
  font-size: 0.8em;
}

.bookmark-time {
  margin: 0;
  color: #999;
  font-size: 0.75em;
}

.bookmark-actions {
  display: flex;
  gap: 5px;
}

.visit-bookmark, .remove-bookmark {
  padding: 5px 10px;
  border: none;
  border-radius: 3px;
  font-size: 0.8em;
  cursor: pointer;
  transition: all 0.2s ease;
}

.visit-bookmark {
  background: #667eea;
  color: white;
}

.visit-bookmark:hover {
  background: #5a6fd8;
}

.remove-bookmark {
  background: #dc3545;
  color: white;
}

.remove-bookmark:hover {
  background: #c82333;
}

.bookmark-actions {
  padding: 15px 20px;
  border-top: 1px solid #e9ecef;
  display: flex;
  gap: 10px;
  justify-content: flex-end;
}

.bookmark-actions button {
  padding: 8px 15px;
  border: none;
  border-radius: 5px;
  cursor: pointer;
  font-size: 0.9em;
  transition: all 0.2s ease;
}

.bookmark-actions .secondary {
  background: #6c757d;
  color: white;
}

.bookmark-actions .secondary:hover {
  background: #5a6268;
}

.bookmark-actions .danger {
  background: #dc3545;
  color: white;
}

.bookmark-actions .danger:hover {
  background: #c82333;
}

/* 页面收藏按钮样式 */
.page-bookmark-button {
  background: transparent;
  border: 1px solid #ddd;
  color: #666;
  padding: 5px 10px;
  border-radius: 15px;
  cursor: pointer;
  font-size: 0.8em;
  transition: all 0.3s ease;
  display: inline-flex;
  align-items: center;
  gap: 5px;
}

.page-bookmark-button:hover {
  border-color: #667eea;
  color: #667eea;
}

.page-bookmark-button.bookmarked {
  background: #ffeb3b;
  border-color: #ffeb3b;
  color: #333;
}

/* 书签通知样式 */
.bookmark-notification {
  position: fixed;
  top: 20px;
  right: 20px;
  background: white;
  border-radius: 8px;
  box-shadow: 0 5px 20px rgba(0, 0, 0, 0.15);
  padding: 15px 20px;
  display: flex;
  align-items: center;
  gap: 10px;
  z-index: 1001;
  transform: translateX(400px);
  opacity: 0;
  transition: all 0.3s ease;
}

.bookmark-notification.show {
  transform: translateX(0);
  opacity: 1;
}

.bookmark-notification-success {
  border-left: 4px solid #28a745;
}

.bookmark-notification-error {
  border-left: 4px solid #dc3545;
}

.bookmark-notification-warning {
  border-left: 4px solid #ffc107;
}

.bookmark-notification-info {
  border-left: 4px solid #17a2b8;
}

.notification-icon {
  font-size: 1.2em;
}

.notification-message {
  color: #333;
  font-weight: 500;
}

/* 书签功能响应式设计 */
@media (max-width: 768px) {
  .bookmark-button {
    top: auto;
    bottom: 20px;
    right: 20px;
  }
  
  .bookmark-panel {
    top: auto;
    bottom: 80px;
    right: 20px;
    left: 20px;
    width: auto;
  }
  
  .bookmark-notification {
    right: 10px;
    left: 10px;
    transform: translateY(-100px);
  }
  
  .bookmark-notification.show {
    transform: translateY(0);
  }
}

/* 书签列表滚动条样式 */
.bookmark-list::-webkit-scrollbar {
  width: 4px;
}

.bookmark-list::-webkit-scrollbar-track {
  background: #f1f1f1;
}

.bookmark-list::-webkit-scrollbar-thumb {
  background: #c1c1c1;
  border-radius: 2px;
}

.bookmark-list::-webkit-scrollbar-thumb:hover {
  background: #a8a8a8;
}

/* 用户反馈系统样式 */
.feedback-button {
    position: fixed;
    bottom: 20px;
    right: 20px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    border: none;
    border-radius: 25px;
    padding: 12px 20px;
    cursor: pointer;
    box-shadow: 0 4px 15px rgba(102, 126, 234, 0.4);
    transition: all 0.3s ease;
    z-index: 1000;
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 14px;
    font-weight: 500;
}

.feedback-button:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(102, 126, 234, 0.6);
}

.feedback-button.active {
    background: linear-gradient(135deg, #764ba2 0%, #667eea 100%);
}

.feedback-icon {
    font-size: 16px;
}

#feedback-form {
    position: fixed;
    bottom: 80px;
    right: 20px;
    width: 350px;
    background: white;
    border-radius: 12px;
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.2);
    z-index: 1001;
    border: 1px solid #e0e0e0;
}

.feedback-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px 20px;
    border-bottom: 1px solid #e0e0e0;
    background: linear-gradient(135deg, #f8f9fa 0%, #e9ecef 100%);
    border-radius: 12px 12px 0 0;
}

.feedback-header h3 {
    margin: 0;
    color: #333;
    font-size: 16px;
}

#close-feedback-form {
    background: none;
    border: none;
    font-size: 18px;
    cursor: pointer;
    color: #666;
    padding: 5px;
}

#close-feedback-form:hover {
    color: #333;
}

.feedback-content {
    padding: 20px;
}

.feedback-type-selector {
    margin-bottom: 20px;
}

.feedback-type-selector label {
    display: block;
    margin-bottom: 10px;
    font-weight: 500;
    color: #333;
}

.feedback-types {
    display: flex;
    gap: 8px;
    flex-wrap: wrap;
}

.feedback-type {
    padding: 8px 12px;
    border: 1px solid #ddd;
    border-radius: 6px;
    background: #f8f9fa;
    cursor: pointer;
    transition: all 0.2s ease;
    font-size: 12px;
}

.feedback-type:hover {
    border-color: #667eea;
}

.feedback-type.active {
    background: #667eea;
    color: white;
    border-color: #667eea;
}

.rating-section {
    margin-bottom: 20px;
}

.rating-section label {
    display: block;
    margin-bottom: 10px;
    font-weight: 500;
    color: #333;
}

.star-rating {
    display: flex;
    gap: 5px;
    margin-bottom: 8px;
}

.star {
    font-size: 24px;
    color: #ddd;
    cursor: pointer;
    transition: color 0.2s ease;
}

.star:hover {
    color: #ffd700;
}

.rating-text {
    font-size: 12px;
    color: #666;
    font-style: italic;
}

.feedback-input-section {
    margin-bottom: 20px;
}

.feedback-input-section label {
    display: block;
    margin-bottom: 8px;
    font-weight: 500;
    color: #333;
}

#feedback-content {
    width: 100%;
    padding: 10px;
    border: 1px solid #ddd;
    border-radius: 6px;
    resize: vertical;
    font-family: inherit;
    font-size: 14px;
}

#feedback-content:focus {
    outline: none;
    border-color: #667eea;
}

.character-count {
    text-align: right;
    font-size: 12px;
    color: #666;
    margin-top: 5px;
}

.contact-section {
    margin-bottom: 20px;
}

.contact-section label {
    display: block;
    margin-bottom: 8px;
    font-weight: 500;
    color: #333;
}

#contact-info {
    width: 100%;
    padding: 10px;
    border: 1px solid #ddd;
    border-radius: 6px;
    font-size: 14px;
}

#contact-info:focus {
    outline: none;
    border-color: #667eea;
}

.feedback-actions {
    display: flex;
    gap: 10px;
}

.feedback-actions button {
    flex: 1;
    padding: 10px;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    font-weight: 500;
    transition: all 0.2s ease;
}

#submit-feedback {
    background: #28a745;
    color: white;
}

#submit-feedback:hover {
    background: #218838;
}

#cancel-feedback {
    background: #6c757d;
    color: white;
}

#cancel-feedback:hover {
    background: #5a6268;
}

.feedback-notification {
    position: fixed;
    top: 20px;
    right: 20px;
    padding: 15px 20px;
    border-radius: 8px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
    z-index: 1002;
    transform: translateX(400px);
    transition: transform 0.3s ease;
    display: flex;
    align-items: center;
    gap: 10px;
}

.feedback-notification.show {
    transform: translateX(0);
}

.feedback-notification-success {
    background: #d4edda;
    color: #155724;
    border: 1px solid #c3e6cb;
}

.feedback-notification-error {
    background: #f8d7da;
    color: #721c24;
    border: 1px solid #f5c6cb;
}

.feedback-notification-warning {
    background: #fff3cd;
    color: #856404;
    border: 1px solid #ffeaa7;
}

.feedback-notification-info {
    background: #d1ecf1;
    color: #0c5460;
    border: 1px solid #bee5eb;
}

.notification-icon {
    font-size: 16px;
}

.notification-message {
    font-size: 14px;
}

/* 移动端反馈系统适配 */
@media (max-width: 768px) {
    .feedback-button {
        bottom: 10px;
        right: 10px;
        padding: 10px 16px;
        font-size: 12px;
    }
    
    #feedback-form {
        width: calc(100% - 40px);
        right: 10px;
        left: 10px;
        bottom: 70px;
    }
    
    .feedback-types {
        justify-content: center;
    }
    
    .feedback-actions {
        flex-direction: column;
    }
}

/* 用户反馈系统样式结束 */

/* 学习进度跟踪系统样式 */
#progress-button {
    position: fixed;
    bottom: 20px;
    right: 20px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    border: none;
    border-radius: 50px;
    padding: 12px 20px;
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.2);
    z-index: 1000;
    display: flex;
    align-items: center;
    gap: 8px;
    transition: all 0.3s ease;
}

#progress-button:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(0, 0, 0, 0.3);
}

#progress-button.active {
    background: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
}

.progress-icon {
    font-size: 18px;
}

#progress-panel {
    position: fixed;
    bottom: 80px;
    right: 20px;
    width: 350px;
    max-height: 500px;
    background: white;
    border-radius: 12px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.3);
    z-index: 1000;
    overflow: hidden;
    display: none;
}

.progress-header {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 15px 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.progress-header h3 {
    margin: 0;
    font-size: 16px;
    font-weight: 600;
}

#close-progress-panel {
    background: none;
    border: none;
    color: white;
    font-size: 18px;
    cursor: pointer;
    padding: 0;
    width: 24px;
    height: 24px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.progress-content {
    padding: 20px;
    max-height: 400px;
    overflow-y: auto;
}

.progress-overview {
    margin-bottom: 20px;
}

.progress-overview h4 {
    margin: 0 0 15px 0;
    font-size: 14px;
    color: #333;
    font-weight: 600;
}

.overview-stats {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 10px;
}

.stat-item {
    text-align: center;
    padding: 10px;
    background: #f8f9fa;
    border-radius: 8px;
}

.stat-value {
    display: block;
    font-size: 18px;
    font-weight: 700;
    color: #667eea;
}

.stat-label {
    font-size: 12px;
    color: #666;
    margin-top: 5px;
}

.progress-bars {
    margin-bottom: 20px;
}

.progress-bars h4 {
    margin: 0 0 15px 0;
    font-size: 14px;
    color: #333;
    font-weight: 600;
}

.progress-bar-item {
    display: flex;
    align-items: center;
    margin-bottom: 12px;
    gap: 10px;
}

.bar-label {
    font-size: 12px;
    color: #666;
    min-width: 80px;
}

.progress-bar {
    flex: 1;
    height: 8px;
    background: #e9ecef;
    border-radius: 4px;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, #4facfe 0%, #00f2fe 100%);
    border-radius: 4px;
    transition: width 0.5s ease;
}

.progress-percentage {
    font-size: 12px;
    font-weight: 600;
    color: #333;
    min-width: 30px;
}

.learning-goals {
    margin-bottom: 20px;
}

.learning-goals h4 {
    margin: 0 0 15px 0;
    font-size: 14px;
    color: #333;
    font-weight: 600;
}

.goals-list {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.goal-item {
    display: flex;
    align-items: center;
    gap: 8px;
}

.goal-checkbox {
    width: 16px;
    height: 16px;
    border-radius: 3px;
    border: 2px solid #ddd;
    cursor: pointer;
}

.goal-checkbox:checked {
    background: #667eea;
    border-color: #667eea;
}

.goal-checkbox:disabled {
    opacity: 0.6;
    cursor: not-allowed;
}

.goal-item label {
    font-size: 12px;
    color: #333;
    cursor: pointer;
}

.personalized-recommendations {
    margin-bottom: 20px;
}

.personalized-recommendations h4 {
    margin: 0 0 15px 0;
    font-size: 14px;
    color: #333;
    font-weight: 600;
}

.recommendations-list {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.recommendation-item {
    display: flex;
    align-items: flex-start;
    gap: 10px;
    padding: 10px;
    background: #f8f9fa;
    border-radius: 8px;
    border-left: 3px solid #667eea;
}

.rec-icon {
    font-size: 16px;
    margin-top: 2px;
}

.rec-content {
    flex: 1;
}

.rec-content strong {
    font-size: 12px;
    color: #333;
    display: block;
    margin-bottom: 5px;
}

.rec-content p {
    font-size: 11px;
    color: #666;
    margin: 0 0 8px 0;
    line-height: 1.4;
}

.rec-action {
    background: #667eea;
    color: white;
    border: none;
    border-radius: 4px;
    padding: 4px 8px;
    font-size: 10px;
    cursor: pointer;
    transition: background 0.3s ease;
}

.rec-action:hover {
    background: #5a6fd8;
}

.no-recommendations {
    font-size: 12px;
    color: #999;
    text-align: center;
    margin: 0;
    padding: 20px 0;
}

.learning-stats {
    margin-bottom: 20px;
}

.learning-stats h4 {
    margin: 0 0 15px 0;
    font-size: 14px;
    color: #333;
    font-weight: 600;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 10px;
}

.stat-card {
    text-align: center;
    padding: 15px 10px;
    background: #f8f9fa;
    border-radius: 8px;
    border: 1px solid #e9ecef;
}

.stat-icon {
    font-size: 20px;
    display: block;
    margin-bottom: 5px;
}

.stat-number {
    display: block;
    font-size: 18px;
    font-weight: 700;
    color: #667eea;
}

.stat-desc {
    font-size: 10px;
    color: #666;
    margin-top: 5px;
}

.progress-actions {
    padding: 15px 20px;
    border-top: 1px solid #e9ecef;
    display: flex;
    gap: 10px;
}

.progress-actions button {
    flex: 1;
    padding: 8px 12px;
    border: none;
    border-radius: 6px;
    font-size: 12px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
}

.progress-actions .secondary {
    background: #6c757d;
    color: white;
}

.progress-actions .secondary:hover {
    background: #5a6268;
}

.progress-actions .danger {
    background: #dc3545;
    color: white;
}

.progress-actions .danger:hover {
    background: #c82333;
}

/* 进度通知样式 */
.progress-notification {
    position: fixed;
    top: 20px;
    right: 20px;
    background: white;
    border-radius: 8px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.2);
    padding: 15px 20px;
    display: flex;
    align-items: center;
    gap: 10px;
    z-index: 1001;
    transform: translateX(400px);
    transition: transform 0.3s ease;
}

.progress-notification.show {
    transform: translateX(0);
}

.progress-notification-success {
    border-left: 4px solid #28a745;
}

.progress-notification-error {
    border-left: 4px solid #dc3545;
}

.progress-notification-warning {
    border-left: 4px solid #ffc107;
}

.progress-notification-info {
    border-left: 4px solid #17a2b8;
}

.notification-icon {
    font-size: 18px;
}

.notification-message {
    font-size: 14px;
    color: #333;
    font-weight: 500;
}

/* 学习进度跟踪系统样式结束 */
